According to the law of conservation of energy, which statement must be true?

A. The total energy of a system can increase only if energy enters the system.

B. A system cannot take in additional matter.

C. The total energy in a system can only decrease over time.

D. Energy that is transferred cannot be transformed into a different type of energy.
​

Maria throws two stones from the top edge of a building at a speed of 20 m/s, The time is mathematically given as

t=4.5 sec.

Generally, the equation for speed  is mathematically given as

V = u+at

Therefore

0 = 22-9.8xt.

t = 22 /9.8 sec

t = 2.24489.

The same time will be taken from max^m height to point O

The extra time is taken

t=4.49 sec.

t=4.5 sec.

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remote control

Explanation:

A remote control uses light waves just beyond the visible spectrum of light—infrared light waves—to change channels on your TV.

Sian wants to count the number of seconds it takes for a beaker's contents to become purple from clear. She should utilize a stopwatch as her instrument for this job.

Watch that, when turned on and off, measures the amount of time that has passed since a specific time.

Sian wants to measure the number of seconds that it takes for the contents of a beaker to change from clear to purple. Stopwatch is the tool she should utilize for this purpose.

Hence, option B is correct.

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Answer: Sian wants to count the number of seconds it takes for a beaker's contents to become purple from clear. She should utilize a stopwatch as her instrument for this job.

option b

Explanation:

#21

According to first equation of kinematics

#22

#a

The order is

#b

for speed find absolute velocity

So order is

S1<S3<S2

Answer:

See below ~

Explanation:

Question 21 :

⇒ v = u + at

⇒ v = 5 + 1.3 (2)

⇒ v = 5 + 2.6

⇒ v = 7.6 m/s

=============================================================

Question 22 : At t = 3

Subpart (a)

⇒ Object 1 : v = 2 + 3(3) = 11 m/s

⇒ Object 2 : v = -8 - 4(3) = -20 m/s

⇒ Object 3 : v = 1 - 5(3) = -14 m/s

⇒ Hence, their velocities are in the order : Object 2 < Object 3 < Object 1

Subpart (b)

⇒ Object 1 : v = | 2 + 3(3) | = 11 m/s

⇒ Object 2 : v = | -8 - 4(3) | = 20 m/s

⇒ Object 3 : v = | 1 - 5(3) | = 14 m/s

⇒ Hence, their speeds are in the order : Object 1 < Object 3 < Object 2

Answer:

g = -3.143 m/s²

Explanation:

To determine acceleration due to the gravitational force, it can be used the following formula:

v = v₀ + gt, where:

v₀ is the initial velocity;

g is acceleration due to gravity

t is the time to return to the point of origin

Answer:

The focal length of a lens is the distance from the lens to the focal point.

For a convex lens the focal point is that point at which parallel rays will be focused after passing thru the lens.

Note:  For a concave lens the rays will diverge after passing thru the lens and will appear to come from a point on the same side of the lens from which the parallel rays strike the lens,

The net force needed to lift a full grocery sack uniformly is 32.115 N.

When two or more forces are acting on the system of objects, then the to attain equilibrium, net force must be zero.

Given the weight of sack W = 210N and the acceleration a = 1.5m/s².

The mass of the sack will be

m = Weight / acceleration due to gravity

m = 210 N/9.81 m/s²

m = 21.41 kg

Using Newton's second law, the net force will be

F = mass x acceleration

F= 21.41 x 1.5

F = 32.115 N

Thus, the net force is 32.115 N.

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Answer:

4.0208 x 10^16 meters

Explanation:

speed of light in m/s   *      # seconds in a year      * 4.25 years =

2.99792 x 10^8   *        3600*24*365.25  *     4.25 = 4.0208 x 10^16 m

From the information provided and the calculations, the energy of the drop is 1.51 eV

The Rydberg formula is used to obtain the energy of a photon or the wavelength of a photon.

Thus;

1/λ = 1.097 * 10^7 (1/3^2 - 1/5^2)

1/λ = 1.097 * 10^7(0.11 - 0.04)

λ = 1.3 * 10^-6 m

Since;

E = hc/λ

E = 6.6 * 10^-34 * 3 * 10^8/1.3 * 10^-6

E = 1.51 * 10^-19 J or 1.51 eV

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Answer:

0.97eV

Explanation:

The energy emitted during n=5 is 0.54 eV

The energy emitted during n=3 is 1.51 eV
(This information is on the Physics Reference Table 2006 edition)

We find the change in the energy level which is:  

1.51eV-0.54eV = 0.97eV

Therefore the energy emitted by the photon is 0.97eV.

If the man DECREASES the force of his push on the cart, the cart slows down.

The force applied to an object is determined by applying Newton's second law of motion.

F = ma

where;

a = Δv/t

F = (mΔv)/t

mΔv = Ft

Δv = Ft/m

From the equation above, when the applied force decreases, the change in velocity decreases.

Thus, if the man DECREASES the force of his push on the cart, the cart slows down.

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Answer: C. Be more dense and flow under warm air.

Explanation:

think of a supermarket selling dairy products and when you open the fridge to get the milk, outside the supermarket is hot and inside the fridge is cold ice.

Answer:

Displacement...

Explanation:

Displacement is a vector quantity as it have both magnitude and direction...

[tex]...[/tex]

a. displacement is the correct answer

Displacement is a vector quantity

Displacement is a vector quantity because it has both magnitude and direction.

Explanation:

Force = mass x acceleration

F= ma (formula)

15N = o.5kg x a

Divide both sides by o.5

a = 30 (greater acceleration)

15N = 4.5kg x a

Divide both sides by 4.5

a= 3.33 (great acceleration)

15N = 0.05kg x a

Divide both sides by 0.05

a = 300 (greatest acceleration)

Answer:

K=6.250 J

Explanation:

m=500kg

v=m/s

Kinetic energy= ½mv²=½(500×25) J= 6.250 J

Cheer dance​ is a routine composed of yells and cheers gymnastic skill and dance.  

Cheer dance or cheerleading is a group activity used to entertain fans at athletic events and inspire louder, more enthusiastic cheering. It combines dancing and acrobatic aspects with shouted phrases.

A never-ending range of diverse stunts, jumps, pyramids, dances, and chants that integrate a variety of different movements can be included in the immensely complex sport of cheerleading. Base, partner, and spotter are the three primary cheerleading roles. These roles are all a part of cheerleading stunts, which pose the greatest risk of harm to participants.

It is a competitive sport and leisure activity made up of a set routine with necessary performance components, much like in gymnastics and dance. Additionally, it hopes to get the crowds to cheer in team sports event.

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Your question is incomplete, but most probably your full question was:

1. It is a routine composed of yells and cheers, gymnastic skills and dance.

A. Contemporary dance

B. Hip-hop dance

C. Street dance

D. Cheer dance​

The reactance of the circuit will be 5.233×10⁻⁴ ohm. Inductive reactance is the product of 2 times π frequency and the coil inductance.

When alternating electricity passes through pure reactance, it causes a voltage drop that is 90 degrees out of phase with the current.

The letter “X” is used to represent reactance in mathematics, and it is measured in ohms.

The inductive reactance of a coil is calculated using the following formula:

Inductive reactance, or XL, is the product of 2 times p (pi), and the frequency of the ac current in hertz, and the coil inductance in henries.

XL= 2πfL

Where,

f {frequency)

L (Inductance)

The reactance of the circuit is found as;

[tex]\rm R_{new}=0.38[{(\frac{1}{60} )^2][/tex]

[tex]\rm R_{new}=1.055 \times 10^{-4} \ ohm[/tex]

The inductance of the circuit is;

[tex]\rm X_{new}=1.9(\frac{1}{60} )^2\\\\X_{new}= 5.233 \times 10^{-4}\ ohm[/tex]

Hence, the reactance of the circuit will be 5.233×10⁻⁴ ohm.

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The time it would take a 2500 W electric kettle to boil away 1.5 Kg of water is 2400 seconds

Use the formula:

Power × time = mass × specific heat

Given mass = 1. 5kg

Specific latent heat of vaporization = 4000000 J/ Kg

Power = 2500 W

Substitute the values into the formula

Power × time = mass × specific heat

2500 × time = 1. 5 × 4000000

Make 'time' the subject

time = 1. 5 × 4000000 ÷ 2500 = 6000000 ÷ 2500 = 2400 seconds

Therefore, the time it would take a 2500 W electric kettle to boil away 1.5 Kg of water is 2400 seconds.

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The direction of a vector that has the following components is 233°.

The direction of a vector is where its endpoint points. However, when at least one of the characteristics mentioned above is different, we say that the vectors are different.

In this case, this calculus will be:

[tex]tan\theta= \frac{59}{44} \\\theta= tan^{-1}(\frac{59}{44})\\ \theta= 233\°[/tex]

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The vector with components x = -44 m and y = -59 m has a direction of approximately 52.16 degrees counterclockwise from the positive x-axis.

The direction of a vector with components x = -44 m and y = -59 m can be determined using trigonometry.  In this case, we have:

x-component (x) = -44 m

y-component (y) = -59 m

We can use the inverse tangent function to find the angle.

The direction angle (θ) can be calculated as:

θ = arctan(y / x)

θ = arctan((-59 m) / (-44 m))

Calculating this expression:

θ ≈ arctan(1.341)

To find the actual angle, we can use a calculator or table to determine the inverse tangent of 1.341.

θ ≈ 52.16 degrees

Therefore, the direction of the vector is approximately 52.16 degrees in the counterclockwise direction from the positive x-axis.

The vector with components x = -44 m and y = -59 m has a direction of approximately 52.16 degrees counterclockwise from the positive x-axis.

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(a) The moment of inertia of the sign for rotation about the side of length h is 1.24 kgm².

(b) The kinetic energy of the sign when it is rotating about an axis is 141.37 J.

The moment of inertia of the sign for rotation about the side of length h is calculated as follows;

I = 2 x ¹/₃M(b/2)²

I = 2 x ¹/₃Mb² x ¹/₄

I = ¹/₆Mb²

I = ¹/₆ x 4.4 x 1.3²

I = 1.24 kgm²

K.E(rot) = ¹/₂Iω²

where;

K.E(rot) = ¹/₂(1.24)(15.1)²

K.E(rot) = 141.37 J

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Answer:

Approximately [tex](-348\; {\rm J})[/tex], assuming that the bike was on level ground.

Explanation:

If an object of mass [tex]m[/tex] is moving at a speed of [tex]v[/tex], the kinetic energy of that object would be [tex](1/2)\, m\, v^{2}[/tex].

At a speed of [tex]v = 3.84\; {\rm m\cdot s^{-1}}[/tex], the kinetic energy of the bike and the cyclist- combined- would be:

[tex]\begin{aligned} &\frac{1}{2}\, m\, v^{2} \\=\; &\frac{1}{2}\times 53.0\; {\rm kg} \times (3.84\; {\rm m\cdot s^{-2}})^{2} \\ \approx \; & 390.76\; {\rm J}\end{aligned}[/tex].

At a speed of [tex]v = 1.27\; {\rm m\cdot s^{-1}}[/tex], the kinetic energy of the bike and the cyclist- combined- would be:

[tex]\begin{aligned} &\frac{1}{2}\, m\, v^{2} \\=\; &\frac{1}{2}\times 53.0\; {\rm kg} \times (1.27\; {\rm m\cdot s^{-2}})^{2} \\ \approx \; &42.741 \; {\rm J}\end{aligned}[/tex].

The energy change was approximately:

[tex]390.76\; {\rm J} - 42.741\; {\rm J} \approx 348\; {\rm J}[/tex].

If the bike was on level ground, the friction on the bike and the cyclist would have done a work of [tex](-348\: {\rm J})[/tex] to reduce the kinetic energy of the bike and the cyclist by that amount.

Answer: C) -348J

Explanation:

42.741 - 390.76 (the kinetic energy of the two speeds) is equal to -348.

The magnitude of the angular acceleration of the magnetic disk is determined as 35 rad/s².

The angular acceleration of the disk is determined from the principle of conservation of angular momentum as follows;

τ = Iα

where;

α is angular acceleration

I is moment of inertia of the disk

I = 0.5MR²

I = 0.5 x 0.2 x 2²

I = 0.4 kgm²

τ = Iα

α = τ/I

α = (14)/(0.4)

α = 35 rad/s²

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Answer:

False

Explanation:

It is actually I = V/R and V = I × R

Use lens formula

The focal length of the lens is 5.8 cm.

To find the focal length, the given values are:

Image distance - 10 cm

Object distance - 14 cm

      The distance between the convex lens or a concave mirror and the focal point of a lens or mirror is called the focal length. This is the parallel line which meet at the distance from the lens or mirror.

                1/Focal length = 1/Image distance + 1/Object distance ( cm )

                                    1/f = 1/v-1/u

                                    1/f = 1/-10-1/14

                                    1/f = -7-5/70

                                    1/f = -12/70

                                      f = 70/-12

                                      f = -5.8cm

The focal length of the lens is - 5.8 cm.

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The frequency of an electromagnetic wave with wavelength of 10nm will be 3 × 10∧7 Hz and would belong to the X-ray or ultraviolet part of the electromagnetic spectrum due to its wavelength

What is frequency?

Frequency is defined as the number of oscillations of a wave per unit time and is measured in hertz(Hz).

It is also inversely proportional to the wavelength.

The frequency of an electromagnetic wave can be calculated using the formula;

frequency = velocity of light divided by the wavelength

f = v ÷ λ

Note that the velocity of light = 3 × 10 ∧8 m/s

Wavelength = 10nm

Frequency, f = 3 × 10∧8 ÷ 10 = 3 × 10∧7 Hz

Hence, the frequency of an electromagnetic wave with wavelength of 10nm will be 3 × 10∧7 Hz and would belong to the X-ray or ultraviolet part of the electromagnetic spectrum due to its wavelength.

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The cross-sectional area of the tape is determined as 3.9 x 10⁻⁵ ft².

The volume of the tape is calculated as follows;

volume = mass/density

volume = (1.95 lb)/(490 lb/ft³)

volume = 3.98 x 10⁻³ ft³

V  = AL

A = V/L

A = 3.98 x 10⁻³ ft³/102 ft

A = 3.9 x 10⁻⁵ ft²

Thus, the cross-sectional area of the tape is determined as 3.9 x 10⁻⁵ ft².

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The diagram is labelled to DRAW the RESULTANT wave and LABEL the areas of interference with CI, DI and/or points of TDI.

When a light ray falls on the interface of two medium like air and water, then the portion of light is reflected and another portion of the light is refracted into the water medium. The angle of incidence is equal to the angle of reflection but the angle of incidence is larger then the angle of refraction.

Open the attached file. It shows 2 waves (a blue one and an orange one) that are moving through the same medium at the same time.

Thus, the diagram is labelled.

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Answer:

  toward the center of the circular curve

Explanation:

An object will follow a circular path at constant speed if and only if its net acceleration is constant and directed toward the center of the curved path.

__

The result force is directed toward the center of the circle.

_____

Additional comment

If any part of the result force is in the direction of motion, the speed will not be constant. If the center-directed force is not constant, the path will not be circular.

Answer:

Explanation:

1800x0.9=1620kg